1. Heat 1 tbsp oil in large skillet set over medium-high heat; cook mushrooms, and pinch of salt and pepper for 6 to 8 minutes or until golden brown and tender. Remove from pan.
2. Add 1 tbsp oil and garlic to pan; cook for 1 minute. Stir in kale, and pinch of salt and pepper. Cook for 3 to 5 minutes or until wilted. Let cool completely.
3. Meanwhile, stir together mayonnaise, lemon zest, lemon juice, 1 tbsp oil, mustard, and remaining each salt and pepper.
4. Preheat CRUX Panini Grill. Spread mayonnaise mixture over 4 slices of bread; layer avocado slices, kale, 1 slice cheese, mushrooms, 2 tomato slices and another cheese slice over top. Cap with remaining bread; brush bread slices on the outside with remaining oil.
5. Wearing oven mitts, carefully open lid of panini grill; center 2 sandwiches on lower grill plate. Press handle several times during cooking time to press sandwich; cook for 5 to 7 minutes or until cheese melts and bread is grill-marked. Carefully remove sandwiches with oven mitts. Repeat with remaining sandwiches. To serve, slice sandwiches in half.